It happened to me several times that an active app got broken because of various reasons (my own doing: removed a device which was used, updated app, etc).
When such a broken app is opened ("settings" view) it is highlighted what is missing, what the problem is, but it would be even better if this app would be highlighted in the "Active Apps" view, one level higher. It would make it obvious when something got broken.

it´s just the list that becomes broken. If i delete one of the smoke sensors or the smoke sensor function,
then the correspodending line is empty. This happens if someone is testing and have many rules with such
a device. For example: If I delete the Lesezimmer - Lesezimmer 20 device then this line is empty.
Also in other apps or rules where I use it, it is gone.
If I have an older scene, rule, whatever it´s called that I don´t remember it would be good to get an information.
Hope you understand.